rule(macro bin_dir_mkdir): correct condition to catch `mkdirat` case
rule(macro bin_dir_mkdir): correct condition to catch `mkdirat` case

Since the dir's path is found:
-  in `evt.arg[1]` for `mkdir`
-  but in `evt.arg[2]` for `mkdirat`
switch to `evt.arg.path` to catch both.
That ensures `Mkdir binary dirs` works properly.

Signed-off-by: Leonardo Grasso <b1c1d8736f20db3fb6c1c66bb1455ed43909f0d8@leonardograsso.com>

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